The disclosure relates to a mixing machine comprising a mixing head with one or more elements for connecting it to a container containing a material to be mixed for forming a closed mixing receptacle containing the material to be mixed. The mixing head is pivotally supported in a frame in such that the mixing receptacle formed by the mixing head and the container can be rotated to carry out the mixing process The mixing head comprises a first rotationally driven tool carried by the mixing head and clearing the bottom of the mixing head for generating a low-energy transport stream for supplying mixed material contained in the mixing receptacle to at least a second tool that is carried by the mixing head and comprises only a fraction of the mixed material contained in the mixing receptacle. The mixing head also includes a transport device for mixing material in a transverse direction to that of the mixing material produced by the first tool, which at least one second tool is responsible for the actual mixing work and is located inside the movement path of the bottom-clearing first tool.
One type of such mixing machines is industrial mixers that are used to mix bulk material. For example, powdery bulk material for preparing mixtures of plastic granular material or in the dye industry. These mixing machines comprise a mixing head pivotably supported in a frame. Such heads serve to both close a container with the mixing material and to connect the mixing head for the purpose of the mixing. A closed mixing receptacle is formed by the container being connected to the mixing head. The mixing head comprises one or more connection elements, such as a peripheral flange, to connect the container to the mixing head. Due to the fact that in these mixing machines the container containing the mixing material is connected to the mixing head, these mixers are also called container mixers. The mixing head itself is pivotably arranged in a frame of the mixing machine so that the mixing can take place in an inverted position relative to the mixing head in which the mixing head is arranged at the bottom and the container connected to it is at the top.
Such previously known container mixers comprise a device for generating a flow of mixing material. In traditional mixers a tool that is axially supported in the mixing head and driven in a rotary manner by a motor serves as a device for generating a flow of mixing material. Such a tool comprises several blades projecting in a radial direction from the drive shaft so that this tool is constructed in the manner of a propeller. Such a container mixer is known from EP 0 225 495 A2. Furthermore, it can be provided that several such tools are arranged on the drive shaft. In the previously known mixers this tool serves as a mixing tool and generates a mixed thrombus in an operation of the mixture with the mixing material contained in the mixing receptacle. The mixing material is centrifuged upward by the mixing tool or tools in an axial range, deflected outward in a radial direction and then conducted back conditioned by gravity on the inner wall of the receptacle to the tools. A flow of mixing material is produced by the previously described mixing tools in which the entire mixing material present in the mixing container is contained. The mixing process takes place due to acceleration of the mixing material on the mixing tool or tools and the turbulences contained in the flow of mixing material.
The attempt is made in industrial mixing machines to achieve the desired thorough mixing in the shortest possible time. Even if a thorough mixing is basically possible in a shorter time with higher tool speeds than with tools that rotate slower, as a rule it should be taken into account that not too much heat should be charged into the material to be mixed. Care should be taken especially in a mixing of plastic granular materials since otherwise the individual particles of granular material cake with each other and/or can also cake on the tools. For this reason the mixing time is limited in the previously described mixing machines in order to prevent that the mixing material becomes too hot by the drive of the mixing tool or tools and by the jacket rubbing of the particles on the inner wall.
A container mixing machine that does not have the disadvantages indicated for the previously described mixing machines is known from EP 2 460 581 A1. This previously known mixing machine operates according to another concept. A slowly rotating, bottom-cleaning first tool serves to supply mixing material to a second tool carried by the mixing head. Very little energy is introduced into the mixing material by the first tool. The second tool is responsible for the actual mixing process. The flow of mixing material generated by the second tool runs in a transverse direction to the flow of transported mixing material made available by the first mixing tool. Since in this mixing machine the actual mixing process is carried out only by the second mixing tool and only a fraction of the mixing material located in the mixing receptacle is impacted by the second mixing tool, this mixing tool can operate with a rapid rotation in order to generate a higher energy flow of secondary mixing material which is the actual flow of mixing material produced for the mixing of the mixing material. Since only a fraction of the mixing material is impacted by the second tool and introduced into the flow of secondary mixing material and the mixing material introduced in it remains in it only for a short time, only a little heat is introduced into the mixing material. Finally, the mixing material particles conducted out of the secondary mixing material flow can cool down before they are resupplied by the first tool to the second tool for further mixing.
The bottom-cleaning transport tool in this previously known mixing machine is constructed like a helical segment whose movement path runs in the radial direction on the outside past the second tool. The helical segment is designed in such a manner that the mixing material cleaned off from the bottom is transported away from the bottom on it. This previously known mixing machine comprises two helical segments that are diametrically opposite one another as regards the axis of rotation.
Even if a considerable reduction of the charging of energy and therefore of heat is achieved during the mixing process with this previously known mixing machine, it would nevertheless be desirable if the charging with heat could be reduced even further.
The foregoing example of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.